1. Field of the Invention
The invention relates to the field of impact ionization avalanche transit time (IMPATT) devices and in particular to a structure for and method of operating a multiquantum well IMPATT device to achieve high power, high efficiency and low noise output in combination with optical injection locking.
2. Description of the Prior Art
High power, low noise, high frequency sources, particularly operating in the millimeter wave range, have many applications in air traffic control radars, communications systems, and modern weapons, typically in missile radars operating in the atmospheric window of 35 and 94 GHz. Normally, a phased locked Gunn oscillator operating at 35 or 94 GHz is used for injection locking in circuits in these types of applications.
However, the efficiency of a single flat gallium arsenide IMPATT device typically falls off dramatically at frequencies above 50 GHz. This is mainly due to the saturation of the ionization rates in the avalanche portions of the device, see T. Misawa, Solid State Electronics, 15(4) pages 457-65 (1972). The marked reduction of the nonlinearity of the avalanche process results in a wide avalanche injection current pulse and is responsible for the reduction in efficiency at high frequencies.
What is needed is a structure for an IMPATT device which can operate at high power levels and high efficiencies at high frequencies in excess of 50 GHz and which can be easily controlled by some type of injection locking.